X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=security%2Fkeys%2Fprocess_keys.c;h=276d27882ce84394d7d6ce5b0c12d82e05f89987;hb=86d9c070175de65890794fa227b68297da6206d8;hp=45b240af6dbe2cd1a9dd22b665e60590e0066a15;hpb=fa623d1b0222adbe8f822e53c08003b9679a410c;p=~andy%2Flinux

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 45b240af6db..276d27882ce 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -17,6 +17,7 @@
 #include <linux/fs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
+#include <linux/user_namespace.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
@@ -34,19 +35,24 @@ struct key_user root_key_user = {
 	.nkeys		= ATOMIC_INIT(2),
 	.nikeys		= ATOMIC_INIT(2),
 	.uid		= 0,
+	.user_ns	= &init_user_ns,
 };
 
 /*****************************************************************************/
 /*
  * install user and user session keyrings for a particular UID
  */
-int install_user_keyrings(struct task_struct *tsk)
+int install_user_keyrings(void)
 {
-	struct user_struct *user = tsk->user;
+	struct user_struct *user;
+	const struct cred *cred;
 	struct key *uid_keyring, *session_keyring;
 	char buf[20];
 	int ret;
 
+	cred = current_cred();
+	user = cred->user;
+
 	kenter("%p{%u}", user, user->uid);
 
 	if (user->uid_keyring) {
@@ -67,7 +73,7 @@ int install_user_keyrings(struct task_struct *tsk)
 		uid_keyring = find_keyring_by_name(buf, true);
 		if (IS_ERR(uid_keyring)) {
 			uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1,
-						    tsk, KEY_ALLOC_IN_QUOTA,
+						    cred, KEY_ALLOC_IN_QUOTA,
 						    NULL);
 			if (IS_ERR(uid_keyring)) {
 				ret = PTR_ERR(uid_keyring);
@@ -83,7 +89,7 @@ int install_user_keyrings(struct task_struct *tsk)
 		if (IS_ERR(session_keyring)) {
 			session_keyring =
 				keyring_alloc(buf, user->uid, (gid_t) -1,
-					      tsk, KEY_ALLOC_IN_QUOTA, NULL);
+					      cred, KEY_ALLOC_IN_QUOTA, NULL);
 			if (IS_ERR(session_keyring)) {
 				ret = PTR_ERR(session_keyring);
 				goto error_release;
@@ -115,140 +121,128 @@ error:
 	return ret;
 }
 
-/*****************************************************************************/
 /*
- * deal with the UID changing
+ * install a fresh thread keyring directly to new credentials
  */
-void switch_uid_keyring(struct user_struct *new_user)
+int install_thread_keyring_to_cred(struct cred *new)
 {
-#if 0 /* do nothing for now */
-	struct key *old;
-
-	/* switch to the new user's session keyring if we were running under
-	 * root's default session keyring */
-	if (new_user->uid != 0 &&
-	    current->session_keyring == &root_session_keyring
-	    ) {
-		atomic_inc(&new_user->session_keyring->usage);
-
-		task_lock(current);
-		old = current->session_keyring;
-		current->session_keyring = new_user->session_keyring;
-		task_unlock(current);
+	struct key *keyring;
 
-		key_put(old);
-	}
-#endif
+	keyring = keyring_alloc("_tid", new->uid, new->gid, new,
+				KEY_ALLOC_QUOTA_OVERRUN, NULL);
+	if (IS_ERR(keyring))
+		return PTR_ERR(keyring);
 
-} /* end switch_uid_keyring() */
+	new->thread_keyring = keyring;
+	return 0;
+}
 
-/*****************************************************************************/
 /*
  * install a fresh thread keyring, discarding the old one
  */
-int install_thread_keyring(struct task_struct *tsk)
+static int install_thread_keyring(void)
 {
-	struct key *keyring, *old;
-	char buf[20];
+	struct cred *new;
 	int ret;
 
-	sprintf(buf, "_tid.%u", tsk->pid);
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
 
-	keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
-				KEY_ALLOC_QUOTA_OVERRUN, NULL);
-	if (IS_ERR(keyring)) {
-		ret = PTR_ERR(keyring);
-		goto error;
+	BUG_ON(new->thread_keyring);
+
+	ret = install_thread_keyring_to_cred(new);
+	if (ret < 0) {
+		abort_creds(new);
+		return ret;
 	}
 
-	task_lock(tsk);
-	old = tsk->thread_keyring;
-	tsk->thread_keyring = keyring;
-	task_unlock(tsk);
+	return commit_creds(new);
+}
 
-	ret = 0;
+/*
+ * install a process keyring directly to a credentials struct
+ * - returns -EEXIST if there was already a process keyring, 0 if one installed,
+ *   and other -ve on any other error
+ */
+int install_process_keyring_to_cred(struct cred *new)
+{
+	struct key *keyring;
+	int ret;
 
-	key_put(old);
-error:
+	if (new->tgcred->process_keyring)
+		return -EEXIST;
+
+	keyring = keyring_alloc("_pid", new->uid, new->gid,
+				new, KEY_ALLOC_QUOTA_OVERRUN, NULL);
+	if (IS_ERR(keyring))
+		return PTR_ERR(keyring);
+
+	spin_lock_irq(&new->tgcred->lock);
+	if (!new->tgcred->process_keyring) {
+		new->tgcred->process_keyring = keyring;
+		keyring = NULL;
+		ret = 0;
+	} else {
+		ret = -EEXIST;
+	}
+	spin_unlock_irq(&new->tgcred->lock);
+	key_put(keyring);
 	return ret;
+}
 
-} /* end install_thread_keyring() */
-
-/*****************************************************************************/
 /*
  * make sure a process keyring is installed
+ * - we
  */
-int install_process_keyring(struct task_struct *tsk)
+static int install_process_keyring(void)
 {
-	struct key *keyring;
-	char buf[20];
+	struct cred *new;
 	int ret;
 
-	might_sleep();
-
-	if (!tsk->signal->process_keyring) {
-		sprintf(buf, "_pid.%u", tsk->tgid);
-
-		keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
-					KEY_ALLOC_QUOTA_OVERRUN, NULL);
-		if (IS_ERR(keyring)) {
-			ret = PTR_ERR(keyring);
-			goto error;
-		}
-
-		/* attach keyring */
-		spin_lock_irq(&tsk->sighand->siglock);
-		if (!tsk->signal->process_keyring) {
-			tsk->signal->process_keyring = keyring;
-			keyring = NULL;
-		}
-		spin_unlock_irq(&tsk->sighand->siglock);
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
 
-		key_put(keyring);
+	ret = install_process_keyring_to_cred(new);
+	if (ret < 0) {
+		abort_creds(new);
+		return ret != -EEXIST ?: 0;
 	}
 
-	ret = 0;
-error:
-	return ret;
-
-} /* end install_process_keyring() */
+	return commit_creds(new);
+}
 
-/*****************************************************************************/
 /*
- * install a session keyring, discarding the old one
- * - if a keyring is not supplied, an empty one is invented
+ * install a session keyring directly to a credentials struct
  */
-static int install_session_keyring(struct task_struct *tsk,
-				   struct key *keyring)
+static int install_session_keyring_to_cred(struct cred *cred,
+					   struct key *keyring)
 {
 	unsigned long flags;
 	struct key *old;
-	char buf[20];
 
 	might_sleep();
 
 	/* create an empty session keyring */
 	if (!keyring) {
-		sprintf(buf, "_ses.%u", tsk->tgid);
-
 		flags = KEY_ALLOC_QUOTA_OVERRUN;
-		if (tsk->signal->session_keyring)
+		if (cred->tgcred->session_keyring)
 			flags = KEY_ALLOC_IN_QUOTA;
 
-		keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
-					flags, NULL);
+		keyring = keyring_alloc("_ses", cred->uid, cred->gid,
+					cred, flags, NULL);
 		if (IS_ERR(keyring))
 			return PTR_ERR(keyring);
-	}
-	else {
+	} else {
 		atomic_inc(&keyring->usage);
 	}
 
 	/* install the keyring */
-	spin_lock_irq(&tsk->sighand->siglock);
-	old = tsk->signal->session_keyring;
-	rcu_assign_pointer(tsk->signal->session_keyring, keyring);
-	spin_unlock_irq(&tsk->sighand->siglock);
+	spin_lock_irq(&cred->tgcred->lock);
+	old = cred->tgcred->session_keyring;
+	rcu_assign_pointer(cred->tgcred->session_keyring, keyring);
+	spin_unlock_irq(&cred->tgcred->lock);
 
 	/* we're using RCU on the pointer, but there's no point synchronising
 	 * on it if it didn't previously point to anything */
@@ -258,110 +252,29 @@ static int install_session_keyring(struct task_struct *tsk,
 	}
 
 	return 0;
+}
 
-} /* end install_session_keyring() */
-
-/*****************************************************************************/
-/*
- * copy the keys in a thread group for fork without CLONE_THREAD
- */
-int copy_thread_group_keys(struct task_struct *tsk)
-{
-	key_check(current->thread_group->session_keyring);
-	key_check(current->thread_group->process_keyring);
-
-	/* no process keyring yet */
-	tsk->signal->process_keyring = NULL;
-
-	/* same session keyring */
-	rcu_read_lock();
-	tsk->signal->session_keyring =
-		key_get(rcu_dereference(current->signal->session_keyring));
-	rcu_read_unlock();
-
-	return 0;
-
-} /* end copy_thread_group_keys() */
-
-/*****************************************************************************/
-/*
- * copy the keys for fork
- */
-int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
-{
-	key_check(tsk->thread_keyring);
-	key_check(tsk->request_key_auth);
-
-	/* no thread keyring yet */
-	tsk->thread_keyring = NULL;
-
-	/* copy the request_key() authorisation for this thread */
-	key_get(tsk->request_key_auth);
-
-	return 0;
-
-} /* end copy_keys() */
-
-/*****************************************************************************/
-/*
- * dispose of thread group keys upon thread group destruction
- */
-void exit_thread_group_keys(struct signal_struct *tg)
-{
-	key_put(tg->session_keyring);
-	key_put(tg->process_keyring);
-
-} /* end exit_thread_group_keys() */
-
-/*****************************************************************************/
-/*
- * dispose of per-thread keys upon thread exit
- */
-void exit_keys(struct task_struct *tsk)
-{
-	key_put(tsk->thread_keyring);
-	key_put(tsk->request_key_auth);
-
-} /* end exit_keys() */
-
-/*****************************************************************************/
 /*
- * deal with execve()
+ * install a session keyring, discarding the old one
+ * - if a keyring is not supplied, an empty one is invented
  */
-int exec_keys(struct task_struct *tsk)
+static int install_session_keyring(struct key *keyring)
 {
-	struct key *old;
-
-	/* newly exec'd tasks don't get a thread keyring */
-	task_lock(tsk);
-	old = tsk->thread_keyring;
-	tsk->thread_keyring = NULL;
-	task_unlock(tsk);
-
-	key_put(old);
-
-	/* discard the process keyring from a newly exec'd task */
-	spin_lock_irq(&tsk->sighand->siglock);
-	old = tsk->signal->process_keyring;
-	tsk->signal->process_keyring = NULL;
-	spin_unlock_irq(&tsk->sighand->siglock);
-
-	key_put(old);
-
-	return 0;
+	struct cred *new;
+	int ret;
 
-} /* end exec_keys() */
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
 
-/*****************************************************************************/
-/*
- * deal with SUID programs
- * - we might want to make this invent a new session keyring
- */
-int suid_keys(struct task_struct *tsk)
-{
-	return 0;
+	ret = install_session_keyring_to_cred(new, NULL);
+	if (ret < 0) {
+		abort_creds(new);
+		return ret;
+	}
 
-} /* end suid_keys() */
+	return commit_creds(new);
+}
 
 /*****************************************************************************/
 /*
@@ -370,10 +283,11 @@ int suid_keys(struct task_struct *tsk)
 void key_fsuid_changed(struct task_struct *tsk)
 {
 	/* update the ownership of the thread keyring */
-	if (tsk->thread_keyring) {
-		down_write(&tsk->thread_keyring->sem);
-		tsk->thread_keyring->uid = tsk->fsuid;
-		up_write(&tsk->thread_keyring->sem);
+	BUG_ON(!tsk->cred);
+	if (tsk->cred->thread_keyring) {
+		down_write(&tsk->cred->thread_keyring->sem);
+		tsk->cred->thread_keyring->uid = tsk->cred->fsuid;
+		up_write(&tsk->cred->thread_keyring->sem);
 	}
 
 } /* end key_fsuid_changed() */
@@ -385,10 +299,11 @@ void key_fsuid_changed(struct task_struct *tsk)
 void key_fsgid_changed(struct task_struct *tsk)
 {
 	/* update the ownership of the thread keyring */
-	if (tsk->thread_keyring) {
-		down_write(&tsk->thread_keyring->sem);
-		tsk->thread_keyring->gid = tsk->fsgid;
-		up_write(&tsk->thread_keyring->sem);
+	BUG_ON(!tsk->cred);
+	if (tsk->cred->thread_keyring) {
+		down_write(&tsk->cred->thread_keyring->sem);
+		tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
+		up_write(&tsk->cred->thread_keyring->sem);
 	}
 
 } /* end key_fsgid_changed() */
@@ -404,7 +319,7 @@ void key_fsgid_changed(struct task_struct *tsk)
 key_ref_t search_process_keyrings(struct key_type *type,
 				  const void *description,
 				  key_match_func_t match,
-				  struct task_struct *context)
+				  const struct cred *cred)
 {
 	struct request_key_auth *rka;
 	key_ref_t key_ref, ret, err;
@@ -423,10 +338,10 @@ key_ref_t search_process_keyrings(struct key_type *type,
 	err = ERR_PTR(-EAGAIN);
 
 	/* search the thread keyring first */
-	if (context->thread_keyring) {
+	if (cred->thread_keyring) {
 		key_ref = keyring_search_aux(
-			make_key_ref(context->thread_keyring, 1),
-			context, type, description, match);
+			make_key_ref(cred->thread_keyring, 1),
+			cred, type, description, match);
 		if (!IS_ERR(key_ref))
 			goto found;
 
@@ -444,10 +359,10 @@ key_ref_t search_process_keyrings(struct key_type *type,
 	}
 
 	/* search the process keyring second */
-	if (context->signal->process_keyring) {
+	if (cred->tgcred->process_keyring) {
 		key_ref = keyring_search_aux(
-			make_key_ref(context->signal->process_keyring, 1),
-			context, type, description, match);
+			make_key_ref(cred->tgcred->process_keyring, 1),
+			cred, type, description, match);
 		if (!IS_ERR(key_ref))
 			goto found;
 
@@ -465,13 +380,13 @@ key_ref_t search_process_keyrings(struct key_type *type,
 	}
 
 	/* search the session keyring */
-	if (context->signal->session_keyring) {
+	if (cred->tgcred->session_keyring) {
 		rcu_read_lock();
 		key_ref = keyring_search_aux(
 			make_key_ref(rcu_dereference(
-					     context->signal->session_keyring),
+					     cred->tgcred->session_keyring),
 				     1),
-			context, type, description, match);
+			cred, type, description, match);
 		rcu_read_unlock();
 
 		if (!IS_ERR(key_ref))
@@ -490,10 +405,10 @@ key_ref_t search_process_keyrings(struct key_type *type,
 		}
 	}
 	/* or search the user-session keyring */
-	else if (context->user->session_keyring) {
+	else if (cred->user->session_keyring) {
 		key_ref = keyring_search_aux(
-			make_key_ref(context->user->session_keyring, 1),
-			context, type, description, match);
+			make_key_ref(cred->user->session_keyring, 1),
+			cred, type, description, match);
 		if (!IS_ERR(key_ref))
 			goto found;
 
@@ -514,20 +429,20 @@ key_ref_t search_process_keyrings(struct key_type *type,
 	 * search the keyrings of the process mentioned there
 	 * - we don't permit access to request_key auth keys via this method
 	 */
-	if (context->request_key_auth &&
-	    context == current &&
+	if (cred->request_key_auth &&
+	    cred == current_cred() &&
 	    type != &key_type_request_key_auth
 	    ) {
 		/* defend against the auth key being revoked */
-		down_read(&context->request_key_auth->sem);
+		down_read(&cred->request_key_auth->sem);
 
-		if (key_validate(context->request_key_auth) == 0) {
-			rka = context->request_key_auth->payload.data;
+		if (key_validate(cred->request_key_auth) == 0) {
+			rka = cred->request_key_auth->payload.data;
 
 			key_ref = search_process_keyrings(type, description,
-							  match, rka->context);
+							  match, rka->cred);
 
-			up_read(&context->request_key_auth->sem);
+			up_read(&cred->request_key_auth->sem);
 
 			if (!IS_ERR(key_ref))
 				goto found;
@@ -544,7 +459,7 @@ key_ref_t search_process_keyrings(struct key_type *type,
 				break;
 			}
 		} else {
-			up_read(&context->request_key_auth->sem);
+			up_read(&cred->request_key_auth->sem);
 		}
 	}
 
@@ -572,93 +487,98 @@ static int lookup_user_key_possessed(const struct key *key, const void *target)
  * - don't create special keyrings unless so requested
  * - partially constructed keys aren't found unless requested
  */
-key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id,
-			  int create, int partial, key_perm_t perm)
+key_ref_t lookup_user_key(key_serial_t id, int create, int partial,
+			  key_perm_t perm)
 {
-	key_ref_t key_ref, skey_ref;
+	struct request_key_auth *rka;
+	const struct cred *cred;
 	struct key *key;
+	key_ref_t key_ref, skey_ref;
 	int ret;
 
-	if (!context)
-		context = current;
-
+try_again:
+	cred = get_current_cred();
 	key_ref = ERR_PTR(-ENOKEY);
 
 	switch (id) {
 	case KEY_SPEC_THREAD_KEYRING:
-		if (!context->thread_keyring) {
+		if (!cred->thread_keyring) {
 			if (!create)
 				goto error;
 
-			ret = install_thread_keyring(context);
+			ret = install_thread_keyring();
 			if (ret < 0) {
 				key = ERR_PTR(ret);
 				goto error;
 			}
+			goto reget_creds;
 		}
 
-		key = context->thread_keyring;
+		key = cred->thread_keyring;
 		atomic_inc(&key->usage);
 		key_ref = make_key_ref(key, 1);
 		break;
 
 	case KEY_SPEC_PROCESS_KEYRING:
-		if (!context->signal->process_keyring) {
+		if (!cred->tgcred->process_keyring) {
 			if (!create)
 				goto error;
 
-			ret = install_process_keyring(context);
+			ret = install_process_keyring();
 			if (ret < 0) {
 				key = ERR_PTR(ret);
 				goto error;
 			}
+			goto reget_creds;
 		}
 
-		key = context->signal->process_keyring;
+		key = cred->tgcred->process_keyring;
 		atomic_inc(&key->usage);
 		key_ref = make_key_ref(key, 1);
 		break;
 
 	case KEY_SPEC_SESSION_KEYRING:
-		if (!context->signal->session_keyring) {
+		if (!cred->tgcred->session_keyring) {
 			/* always install a session keyring upon access if one
 			 * doesn't exist yet */
-			ret = install_user_keyrings(context);
+			ret = install_user_keyrings();
 			if (ret < 0)
 				goto error;
 			ret = install_session_keyring(
-				context, context->user->session_keyring);
+				cred->user->session_keyring);
+
 			if (ret < 0)
 				goto error;
+			goto reget_creds;
 		}
 
 		rcu_read_lock();
-		key = rcu_dereference(context->signal->session_keyring);
+		key = rcu_dereference(cred->tgcred->session_keyring);
 		atomic_inc(&key->usage);
 		rcu_read_unlock();
 		key_ref = make_key_ref(key, 1);
 		break;
 
 	case KEY_SPEC_USER_KEYRING:
-		if (!context->user->uid_keyring) {
-			ret = install_user_keyrings(context);
+		if (!cred->user->uid_keyring) {
+			ret = install_user_keyrings();
 			if (ret < 0)
 				goto error;
 		}
 
-		key = context->user->uid_keyring;
+		key = cred->user->uid_keyring;
 		atomic_inc(&key->usage);
 		key_ref = make_key_ref(key, 1);
 		break;
 
 	case KEY_SPEC_USER_SESSION_KEYRING:
-		if (!context->user->session_keyring) {
-			ret = install_user_keyrings(context);
+		if (!cred->user->session_keyring) {
+			ret = install_user_keyrings();
 			if (ret < 0)
 				goto error;
 		}
 
-		key = context->user->session_keyring;
+		key = cred->user->session_keyring;
 		atomic_inc(&key->usage);
 		key_ref = make_key_ref(key, 1);
 		break;
@@ -669,7 +589,7 @@ key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id,
 		goto error;
 
 	case KEY_SPEC_REQKEY_AUTH_KEY:
-		key = context->request_key_auth;
+		key = cred->request_key_auth;
 		if (!key)
 			goto error;
 
@@ -677,6 +597,25 @@ key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id,
 		key_ref = make_key_ref(key, 1);
 		break;
 
+	case KEY_SPEC_REQUESTOR_KEYRING:
+		if (!cred->request_key_auth)
+			goto error;
+
+		down_read(&cred->request_key_auth->sem);
+		if (cred->request_key_auth->flags & KEY_FLAG_REVOKED) {
+			key_ref = ERR_PTR(-EKEYREVOKED);
+			key = NULL;
+		} else {
+			rka = cred->request_key_auth->payload.data;
+			key = rka->dest_keyring;
+			atomic_inc(&key->usage);
+		}
+		up_read(&cred->request_key_auth->sem);
+		if (!key)
+			goto error;
+		key_ref = make_key_ref(key, 1);
+		break;
+
 	default:
 		key_ref = ERR_PTR(-EINVAL);
 		if (id < 1)
@@ -693,7 +632,7 @@ key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id,
 		/* check to see if we possess the key */
 		skey_ref = search_process_keyrings(key->type, key,
 						   lookup_user_key_possessed,
-						   current);
+						   cred);
 
 		if (!IS_ERR(skey_ref)) {
 			key_put(key);
@@ -725,11 +664,12 @@ key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id,
 		goto invalid_key;
 
 	/* check the permissions */
-	ret = key_task_permission(key_ref, context, perm);
+	ret = key_task_permission(key_ref, cred, perm);
 	if (ret < 0)
 		goto invalid_key;
 
 error:
+	put_cred(cred);
 	return key_ref;
 
 invalid_key:
@@ -737,6 +677,12 @@ invalid_key:
 	key_ref = ERR_PTR(ret);
 	goto error;
 
+	/* if we attempted to install a keyring, then it may have caused new
+	 * creds to be installed */
+reget_creds:
+	put_cred(cred);
+	goto try_again;
+
 } /* end lookup_user_key() */
 
 /*****************************************************************************/
@@ -748,20 +694,33 @@ invalid_key:
  */
 long join_session_keyring(const char *name)
 {
-	struct task_struct *tsk = current;
+	const struct cred *old;
+	struct cred *new;
 	struct key *keyring;
-	long ret;
+	long ret, serial;
+
+	/* only permit this if there's a single thread in the thread group -
+	 * this avoids us having to adjust the creds on all threads and risking
+	 * ENOMEM */
+	if (!is_single_threaded(current))
+		return -EMLINK;
+
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
+	old = current_cred();
 
 	/* if no name is provided, install an anonymous keyring */
 	if (!name) {
-		ret = install_session_keyring(tsk, NULL);
+		ret = install_session_keyring_to_cred(new, NULL);
 		if (ret < 0)
 			goto error;
 
-		rcu_read_lock();
-		ret = rcu_dereference(tsk->signal->session_keyring)->serial;
-		rcu_read_unlock();
-		goto error;
+		serial = new->tgcred->session_keyring->serial;
+		ret = commit_creds(new);
+		if (ret == 0)
+			ret = serial;
+		goto okay;
 	}
 
 	/* allow the user to join or create a named keyring */
@@ -771,29 +730,33 @@ long join_session_keyring(const char *name)
 	keyring = find_keyring_by_name(name, false);
 	if (PTR_ERR(keyring) == -ENOKEY) {
 		/* not found - try and create a new one */
-		keyring = keyring_alloc(name, tsk->uid, tsk->gid, tsk,
+		keyring = keyring_alloc(name, old->uid, old->gid, old,
 					KEY_ALLOC_IN_QUOTA, NULL);
 		if (IS_ERR(keyring)) {
 			ret = PTR_ERR(keyring);
 			goto error2;
 		}
-	}
-	else if (IS_ERR(keyring)) {
+	} else if (IS_ERR(keyring)) {
 		ret = PTR_ERR(keyring);
 		goto error2;
 	}
 
 	/* we've got a keyring - now to install it */
-	ret = install_session_keyring(tsk, keyring);
+	ret = install_session_keyring_to_cred(new, keyring);
 	if (ret < 0)
 		goto error2;
 
+	commit_creds(new);
+	mutex_unlock(&key_session_mutex);
+
 	ret = keyring->serial;
 	key_put(keyring);
+okay:
+	return ret;
 
 error2:
 	mutex_unlock(&key_session_mutex);
 error:
+	abort_creds(new);
 	return ret;
-
-} /* end join_session_keyring() */
+}